Yarn treating jet

ABSTRACT

A yarn treating jet comprising a body member and a cover clamped together. There is a longitudinal passage recessed in the surface of the body that is contiguous with the cover with two opposed fluid conduits in communication with the passage for supplying treating fluid to yarn passing through the passage. The passage includes successively, a tapered length, a straight length of one depth and a converging throat region of a greater depth. The opposed fluid conduits enter the throat region at the parallel to the longitudinal axis of the passage. This passage arrangement along with a raised tapered land extending centrally through the throat region, provides a smooth acceleration of the fluid as it meets the threadline to avoid undue buffeting of the threadline in the jet passage and formation of neps.

United States Patent Bowen [54] YARN TREATING JET [72] Inventor: William W. Bowen, Wilmington,

Del.

[73] Assignee: E. I. du Pont de Nemours and Company, Wilmington, Del.

[22'] Filed: July 27, 1971 [2]] App]. No.: 166,469

52 us. Cl. ..2s/1.4 51 int. Cl. ..D02g 1/16 58 Field of Search ..28/l.4, 72.12

[56] References Cited UNITED STATES PATENTS 3,638,291 2/1972 Ynqve ..2s/1.4

[ Nov. 2, 1972 Prirriiz ry Examiner-Louis K. Rimrodt AttbrnEj-J-lowiud P. West, Jr.

ABSTRACT A yarn treating jet comprising a body member and a cover clamped together. There is a longitudinal passage recessed in the surface of the body that is contiguous with the cover with two opposed fluid conduits in communication with the passage for supplying treating fluid to yarn passing through the passage. The passage includes successively, a tapered length, a straight length of one depth and a converging throat region of a greater depth. The opposed fluid conduits enter the throat region at the parallel to the longitudinal axis of the passage. This passage arrangement along with a raised tapered land extending centrally through the throat region, provides a smooth acceleration of the fluid as it meets the threadline to avoid undue buffeting of the threadline in the jet passage and formation of neps.

D a n Fi ures PATENTED I972 v 3,703,751

' sum 10F2 FIG. I

WILLIAI I. BOWEN BY'WI M/MZ XQ ATTORNEY V INVENTOR PATENTEDunvza 1912 SHEET 2 OF 2 INVENTOR WILLIAM W. BOWEN A ORNEY I YARN 'IREATINGJET BACKGROUND OF THE INVENTION This invention relates to an apparatus for. treating synthetic filaments with hot gas or steam. More particularly, it concerns jet apparatus for forwarding, heating and relaxing filaments which develop crimp spontaneously under such conditions and performing these functions uniformly at high speeds while avoiding knots and tangles. I

Tubular jet apparatus for forwarding and developing crimp in bicomponent filaments is disclosed in Olson U. S. Pat. No. 3,558,760. Such apparatus is suitable for use on drawtwisters where the yarn may be strung up through the jet while the twister is stopped and where the maximum operating speed is below 1000 yards per minute. However, modern production processes wherein multiple ends of yarn are spun, drawn, relaxed and wound continuously atspeeds considerably above 1000 yards per minute requires inserting yarns into a jet while running at full operating speed. When the prior art tubular jets are operated at higher fluid pressures and temperatures in an attempt to forward the yarn at an increased speed and to heat it uniformly in the reduced residence time available, several undesirable effects are noted. First, an increased amount of fluidflows back out the yarn inlet passage countercurrent to the yarn motion which, in effect, reduces the yarn forwarding tension. Where a yarn contains an occasional broken filament, such blowback prevents the broken 'end from feeding through the jet, thus building up afluff-ball'which eventually plugs the jet and breaks down the threadline. Second, the fluid impinging on the yarn becomes much more turbulent, buffeting the yarn against the hot walls of the cavity, subjecting the yarn to highly erratic tensions while it is attempting to develop crimp and entangling the filaments to such an extent that knots (known as neps in the trade) are formed.

A jet apparatus adapted for easy stringup of yarn ends at high speed has been disclosed by Coon in U. S. Pat. No. 3,525,134;,but since the purpose of that jet apparatus was to produce irregular random crimp in filaments having little or no self-crimping tendency and to entangle the filaments to produce a cohesive crimped yarn bundle, the apparatus was designed to maximize turbulence, while on the other hand, it is the purpose of the jet apparatus of this invention to avoid such turbulence and formation of neps while allowing crimp to develop uniformly.

SUMMARY OF THE INVENTION passage including successively, a tapered length, a

straight length of one depth, an enlarged throat region of a greater depth and a continuouslyexpanding treatment chamber, said conduits include successive converging and parallel lengths of said greater depth, said parallel lengths entering said throat region at the same location as said straight length and parallel thereto; and

a raised tapered land extending from said Straight length centrally through said throat region, said land having a width less than said throat region and a thickness of about the difference between said one depth and said greater depth. The yarn treatment channel extends downstream of the minimum area section and extends both widthwise and depthwise with an in- 'cluded angle of less than 1 for a distance at least 20 times the minimum channel width. The downstream end of each treatment channel abruptly enters a diffuser section comprising at least one channel of larger cross sectional area than the threatment channel, and preferably a series of such channels, each wider and deeper than the preceding.

BRIEF DESCRIPTION OF THE DRAWINGS DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 1 As shown in FIGS. 1, 2 and 3, the jet device is composed of a body 10 and detachable cover 12 which is secured to the body by threaded fasteners 14 which extend through apertures 16 into threaded holes 18. Internal supply manifold 22 within the body 10 furnishes pressurized treatment fluid from a source (not shown) to fluid supply conduits 24, 26 in communication with yarn passage 21. These fluid supply conduits are of rectangular cross section and constant depth and include successive converging and parallel lengths 23, 25 and 27, 29, respectively. Preferably, the walls of converging lengths 23, 27 should accelerate the flow of fluid at an approximately constant rate. Yarn passage 21 is of rectangular cross section along its length and includes successively, tapered and cylindrical lengths 17, 19, a converging throat region 28 and an expanding treatment chamber 30 terminating at diffuser 32 which includes successive parallel sided portions 34-42 each wider and deeper than the preceding portion. Yarn 20 enters the passage 21 of jet device through tapered length 17 and a straight length 19, the latter length being cut to approximately half the depth of fluid conduits 24, 26 and throat region 28 with its width being just great enough to pass the yarn 20. The upstanding walls defining the straight length 19 at its downstream end are parallel to the parallel lengths 25, 29 of the fluid conduits 24, 26. A raised tapered land 15 extends downstream from the straight length 19 to or slightly downstream of the minimum area section 31 of throat region 28 and in effect extends the bottom surface of length 19 to about location 31. The land has a thickness that is approximately equal to the difference between the depth of throat region 28 and straight length 19. At location 31, the depth of the yarn passage is greater than length 19 and the same as that of the two fluid conduits 24, 26 and is approximately twice the width of one fluid conduit, as measured at its parallel length 25 or 29. From location 31, yarn treatment chamber 30 expands at an included angle less than 1. This expansion may be widthwise or depthwide but preferably is both. The degree of expansion should preferably be just sufficient to offset viscous drag, thus maintaining constant Mach number. Such a preferred expansion is expressed by the formula dA/A (kM /2) 4f(dx/D) where dA associated area change A initial area k ratio of specific heats (for air k= 1.4)

M desired Mach number (in this case, subsonic fluid velocity of 0.8 is optimum, 0.6 to 0.9 being the preferred range) f friction coefficient. This value is dependent on channel Reynolds number and cross-section (0.006 is a typical value).

dx computed lengths of channel D hydraulic diameter which is equivalent to 4 (flow cross section area/wetted perimeter) Yarn treatment chamber 30 terminates at diffuser 32, which may consist of one or more parallel-sided sections 34-42 larger than yarn treatment chamber 30 in both width and depth. Preferably, the cross sectional area of 34 should be 1.5 to 3.7 times that of yarn chamber 30 at its terminal end where it joins diffuser 32.

Referring to FIG. 3 which shows a portion of a jet constructed for treating multiple yarns, the outer fluid manifold sections 22 should have approximately half the cross sectional area of inner fluid manifold sections 22' each of which supplies two fluid conduits.

EXAMPLES Typical dimensions for converging lengths 23, 27 of fluid conduits 24, 26 are illustrated by the following Examples. One side of the constant-depth conduits is straight. Dimension W (inches) is the width of the conduit measured perpendicularly to the straight side at each distance L (inches) upstream from the point at which the width equals that of the parallel lengths 25, 29 (designated P in the table). The depth of the channel in Example 1 is 0.050 inch and in Example 2 is 0.090 inch.

EXAMPLE 1 L W Relation to P 0.301 0.083 1.80 P 0.251 0.068 1.48 P 0.201 0.061 1.33 P 0.151 0.056 1.22 P 0.101 0.051 1.11P

EXAMPLE 2 L W Relation to P 0.580 0.160 1.78 P 0.480 0.126 1.40 P 0.380 0.105 1.17P 0.280 0.098 1.09 P 0.180 0.093 1.035 P 0.080 0.090 P The smooth acceleration of the fluid provided by the converging sections of the fluid supply channels, the gentle convergence of the streams where they meet the thread-line, the lack of abrupt bends in the channels, the constant Mach number expansion in the yarn treatment channel, and the maintenance of subsonic flow avoid severe bufieting and shaking of the threadline in the jet, allowing crimp to develop uniformly and avoiding neps. The preferred dimensional relationships allow the apparatus to develop adequate forwarding power while reducing or eliminating blowback of fluid out the yarn entrance so that occasional broken filaments may pass through the jet. The stepped diffuser section decelerates the exiting fluid stably so that it is travelling only slightly faster than the yarn at the jet exit. It has been found that 45 denier 7 filament bicomponent yarn can be processed at a yarn speed at the jet entrance at least as high as 3260 yards per minute with a jet of this invention at a nep level of 1.0 neps per million end yards.

What is claimed is:

1. A yarn treating jet comprising: a body and a cover fastened together, said body having a longitudinal passage recessed in its surface contiguous with the cover, through which yarn passes for treatment, two opposed fluid conduits of rectangular cross section in communication with said passage; a fluid supply means connected to the conduits; said passage being of rectangular cross section along its length and including successively, a tapered length, a straight length of one depth, an enlarged throat region of a greater depth, a continuously expanding treatment chamber and a diffuser having a depth and a width greater than said treatment chamber, said conduits include successive converging and parallel lengths of said greater depth, said parallel lengths entering said throat region at the same location as said straight length and parallel thereto; and a raised tapered land extending from said straight length centrally through the throat region, said land having a width less than said throat region and a thickness of about the difference between said one depth and said greater depth. 

1. A yarn treating jet comprising: a body and a cover fastened together, said body having a longitudinal passage recessed in its surface contiguous with the cover, through which yarn passes for treatment, two opposed fluid conduits of rectangular cross section in communication with said passage; a fluid supply means connected to the conduits; said passage being of rectangular cross section along its length and including successively, a tapered length, a straIght length of one depth, an enlarged throat region of a greater depth, a continuously expanding treatment chamber and a diffuser having a depth and a width greater than said treatment chamber, said conduits include successive converging and parallel lengths of said greater depth, said parallel lengths entering said throat region at the same location as said straight length and parallel thereto; and a raised tapered land extending from said straight length centrally through the throat region, said land having a width less than said throat region and a thickness of about the difference between said one depth and said greater depth. 